| Cover Page | Apr. 13, 2020 | Nov. 01, 2019 |
| Entity Information [Line Items] | ||
| Document Type | 8-K | |
| Document Period End Date | Apr. 13, 2020 | |
| Entity File Number | 001-32462 | |
| Entity Registrant Name | PNM Resources, Inc. | |
| Entity Tax Identification Number | 85-0468296 | |
| Entity Incorporation, State or Country Code | NM | |
| Entity Address, Address Line One | 414 Silver Ave. SW | |
| Entity Address, City or Town | Albuquerque | |
| Entity Address, State or Province | NM | |
| Entity Address, Postal Zip Code | 87102-3289 | |
| City Area Code | 505 | |
| Local Phone Number | 241-2700 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Title of 12(b) Security | Common Stock, no par value | |
| Trading Symbol | PNM | |
| Security Exchange Name | NYSE | |
| Entity Emerging Growth Company | false | |
| Entity Central Index Key | 0001108426 | |
| Amendment Flag | false | |
| PNM | ||
| Entity Information [Line Items] | ||
| Entity File Number | 001-06986 | |
| Entity Registrant Name | PUBLIC SERVICE CO OF NEW MEXICO | |
| Entity Tax Identification Number | 85-0019030 | |
| Entity Address, Address Line One | 414 Silver Ave. SW | |
| Entity Address, City or Town | Albuquerque | |
| Entity Address, State or Province | NM | |
| Entity Address, Postal Zip Code | 87102-3289 | |
| City Area Code | 505 | |
| Local Phone Number | 241-2700 | |
| Texas-New Mexico Power Company | ||
| Entity Information [Line Items] | ||
| Entity File Number | 002-97230 | |
| Entity Registrant Name | Texas-New Mexico Power Company | |
| Entity Tax Identification Number | 75-0204070 | |
| Entity Address, Address Line One | 577 N. Garden Ridge Blvd. | |
| Entity Address, City or Town | Lewisville | |
| Entity Address, State or Province | TX | |
| Entity Address, Postal Zip Code | 75067 | |
| City Area Code | 972 | |
| Local Phone Number | 420-4189 |
